The present invention relates to a mass spectrometer and a method of assembling a mass spectrometer.
It is known to use an O-ring seal to provide a gas or vacuum seal between two vacuum chambers or differential pumping regions of a mass spectrometer. The O-ring seals are conventionally manufactured from VITON® or another similar elastomer material. O-ring seals are readily available, come in a range of sizes/dimensions and are relatively inexpensive. However, in certain applications the circular cross sectional profile of the known O-ring seal is not ideal.
In conventional mass spectrometers O-ring seals which are located between two vacuum chambers are compressed under a mechanical load which is provided by, for example, screw fixings. The conventional O-ring seals deform under compression in order to provide a gas/vacuum seal.
One particular problem with conventional O-ring seals is that they require tight tolerance control and it can be hard for a user to insert and remove an O-ring seal from its intended position. This is particularly problematic if the O-ring seals are provided in section of a mass spectrometer which requires regular disassembly in order to service and maintain the mass spectrometer.
In particular, a substantial force is commonly required in order to insert and remove conventional O-ring seals from their sealing location. The force required is often beyond user comfort levels.
US2010/0301207 (Micromass) discloses an improved seal between a mass spectrometer and a hinged ion source. A seal having a substantially rectangular base and an arcuate domed exposed portion is mounted in a groove on the ion source enclosure. The arcuate domed exposed portion protrudes from the groove in an axial direction (i.e. in a direction perpendicular to the plane in which the seal lies), such that when the ion source is closed, the seal is axially compressed against the seal face of the mass spectrometer.
Although the seal disclosed in US2010/0301207 is advantageous in its own right, the Applicants believe that there remains scope for improvements to annular vacuum chamber seals for mass spectrometers.
It is desired to provide an improved mass spectrometer.